Brightening the Night with Day/Night Cameras
Ain’t it funny how the night moves. When you just don’t seem to have as much to lose.
Bob Seger might know how to sing a great tune, but enterprise security leaders know better: When the sun goes down, bad things can happen.
Security video under low light, no light and harsh conditions has come a long way from a time of expensive cameras, illuminators, high-priced installation and, unfortunately back then, poor images. And, while outdoor applications to protect perimeters at night are an obvious solution, the technology also has uses indoors.
Over the years, numerous camera makers have introduced and improved day/night cameras. With sensor improvements and image processing advances, there are dramatic improvements in handling poorly lit scenes. Improved noise reduction, reduced motion blur and the addition of color in near-dark scenarios make low light cameras a significant cost savings trend because the need for additional lighting is reduced.
But not in all cases.
A Matter of Light
In situations where auxiliary lighting is required, covert and semi-covert infrared (IR) illumination extends a camera’s application range. In addition, lower cost thermal network cameras extend the perimeter surveillance range of many facilities to areas where vulnerabilities existed previously.
There are challenges, however. So-called night vision devices have the same drawbacks that daylight and low light cameras do; they need enough light and enough contrast to create usable images. Imagers, really infrared, forward looking infrared and thermal sensors, on the other hand, see more clearly in low light and no light conditions, while creating their own contrast.
Some low light advances come from firms with expertise in night vision.
Photonis USA, as one example, has Nocturn, a new extreme low light CMOS camera for performance under both daylight and low light level conditions. Such gear, small size, weight and power provides monochrome real-time imaging capabilities from daylight to bright starlight in the visible and near infrared spectrum.
And, like any security system, there is more than the camera. Elements include detector resolution, optics and image processing.
For instance, day/night camera lenses must have a proper IR coating to reduce focal shift between day and night. These cameras are designed to “see” visible light and IR light, both of which are present in most light sources. Without the proper IR coating, the red, green and blue color filters that light passes through also allow IR light to pass through, creating an image that is clear at night but blurry during the day. The farther out the view is, the more drastic the focus shift. So a “true” day/night camera physically switches its IR filter out of the lens’ light path, enabling the camera to see IR light, whether naturally occurring or artificial. And because street lights, the sun, the moon and other visible light sources include IR light, a day/night camera can easily capture and record its field of vision. The day/night lenses required by these cameras to maintain proper focus in all light are more complex and therefore more expensive.
Differences Among Choices
In addition, not all thermal security cameras are created equal. Simply comparing manufacturer’s specifications won’t link to the most effective imagers and missions. The bottom line is that image quality matters.
That is the lesson learned by Heifer International in Little Rock, Ark. The new system at Heifer International provides surveillance for three buildings, and cameras are monitored by a central guard station. The IP-based system also makes it possible for multiple departments to monitor their areas, according to Tom Spinnato, facilities/IT specialist for the company. Among technology, there are three Arecont Vision day/night 8-megapixel H.264 cameras.
In another night video application that highlights a solution beyond security, the Friends of Island Beach State Park, N.J., installed a special video surveillance system to monitor osprey nest activity, including their nesting at night.
“Our company specializes in solar-powered, very high resolution HDTV cameras for many different markets. The osprey system was a great challenge. What the state was offering at the time was too low-resolution and had no night vision, so we took on the cause,” says James Sessions of integrator JES Hardware Solutions.
For his client, Sessions selected low-voltage, infrared illuminators from Raytec Systems, installed alongside a PTZ dome network camera. Solar panels at the base of the column charge two batteries during daylight hours so that the camera and lighting could run at night. The Raytec lighting produced IR illumination, enabling the camera to generate high-quality black-and-white images of the nest in total darkness. The quantity and quality of the illumination needed to be sufficient enough to allow the video surveillance system to produce high-quality footage at full frame rate.
Not surprisingly, networking continues to impact security video, whether outdoors, indoors or low light. According to John Edwards, director of remote surveillance technology at Day & Zimmermann, “With megapixel cameras, IP and analytics, security departments are working more closely with IT.” And when it comes to lighting challenges, Edwards urges security end users and their integrators “learn the scene,” which will be viewed, to best understand what technology will best handle it.
There are advances in clear color video in low light conditions, too. One example is Axis’ Lightfinder technology to overcome the belief that analog cameras perform better in low light. The approach uses a CMOS sensor packaged with a lens and “at the edge” processing.
Not Just Lux Ratings
Such designs also emphasize the danger of relying just on lux ratings. If a camera doesn’t get enough light, image quality suffers, which is especially troublesome when using video analytics because the analytics may not work properly, potentially missing an intruder or causing false alarms.
One example is Canberra Stadium, the sporting and event venue in Australia’s capital city. To monitor patrons and vehicles, the stadium installed an HD surveillance system to achieve positive identification day and night, including facial and license plate recognition capabilities. “We have been able to achieve positive identification, even at night, since deploying the system,” says James Kiwi, events and operations manager for the Territory Venues and Events Enterprises Services Division of the Australian Department of Territory and Municipal Services.
Thermal cameras can be put together in an integrated approach, too. For instance, a FLIR thermal fence security system is a combination of thermal security cameras, video analytics software, and other intrusion detection sensors in a scalable, customizable design. With the package, you can create a fully integrated perimeter security solution that provides intrusion detection and instant visual alarm assessment capability while minimizing false alarms.
In its simplest form, such thermal fences could be a single thermal security camera and a box of software. Or with more complex designs, there is integration of many thermal cameras, more traditional security cameras, and non-video alarm sensors like shaker fences and RFIDs on an existing IP network.
This article was previously published in the print magazine as "Brightening Up the Night."
Texas Big, Texas Smart
So Sawyer focused on actionable intelligence from BRS Labs. “It’s been a pleasant surprise for us. You install it on the camera, and you don’t get much out of it on Day 1, but the camera gets smarter and improves over time. So it’s basically become an enterprise specification for me, because the cameras now have the ability to provide intelligence on behavior anomalies that traditional analytics just aren’t designed for.”
He adds that “cameras are not our end-all,” so he seeks simplicity with “ease of setup, use and quick training of staff. I don’t like a lot of bells and whistles.” Unlike previous video analysis tools, which relied on instructions from human programmers, the new system forms its own conclusions based on its own observations. “It has led directly to arrests,” says Sawyer. “It gets smarter the longer it’s there.”
Shutter the Thought
According to a white paper from DRS Technologies, thermal cameras generate a video image by detecting infrared energy (heat) from the scene and converting this energy into an electrical signal. When the shutter closes, it blocks the thermal energy from the scene and creates a uniform thermal reference for the detector to view. A calibration is then performed to ensure that the output of every pixel is the same when viewing this uniform reference. When the shutter is opened and the detector is once again exposed to the scene, the result is a more accurate depiction of the thermal scene. This entire calibration process happens in a fraction of a second. Pixels drift over time and behave differently in various environments, so the shutter is used periodically – typically once every five to 15 minutes depending on the application.
“Thermal was once cost prohibitive” for many applications, points out Todd Brown of DRS. “But no more. You can use the technology for reliable detection outdoors but indoors, too, for some unique applications. Look for consistent images that don’t degrade,” he advises.
While camera systems are effective for visual assessment over wide areas, at night their impact can drop dramatically. Active illumination systems operate only over limited areas, making detection at a distance less likely. Thermal cameras, on the other hand, can be effective day and night because they produce sharp video images from infrared (heat) rays that are emitted by people, structures and objects, whatever the ambient temperature may be. As a result, they can detect potential security threats from great distances, day and night, in areas with no visible light and in conditions of dust, haze, light fog or smoke.
Dam It with LED Illuminators
Lighting covering a wide range can provide higher level security but also meet environmental needs. Energy efficient infrared LED lighting technology, for instance, is part of security video at the historic Tunnel Dam on the Niangua River in Camden County, Mo. Covert infrared light has been deployed instead of visible white light because the dam is located in an area of outstanding natural beauty and the system designers wanted to avoid unnecessary light pollution.
The technology includes ultra wide angle illuminators that light the entire area up to 1,200 feet away, with the capability of providing angles of up to 180 degrees. The units allow the site surveillance system to capture quality images at night, but because the IR light is invisible to the human eye the scene looks totally dark.
Traditional lighting, such as halogen and metal halide, often accounts for a large proportion of electricity consumption, running and maintenance costs in any security system. So LED illuminators offer an efficient change for the dam.